Physico-chemical tailoring of finger millet starch film for improved barrier and mechanical performance

Finger millet starch (NFS) was modified with a novel integrated citric acid (CA) (3, 5, and 8% w/w of total dry starch) and dry heat treatment (DHT) at 130 °C for 5 h. Thin films were prepared from NFS, and modified starch (MFS) was prepared using a solvent casting method. The functional, thermal, and structural properties of thin films were comprehensively analyzed. The thin films made with NFS exhibit a water vapor barrier of 3.81 ± 0.05 g s⁻¹ m⁻¹ Pa⁻¹, which is significantly higher than the water vapor barrier of 1.65 ± 0.43 g s⁻¹ m⁻¹ Pa⁻¹ of the thin films with MFS. Similarly, the tensile strength of the thin film made with NFS is 9.24 ± 0.514 MPa, while that of the thin film made with MFS is 29.82 ± 0.229 MPa. FTIR confirms the esterification in the starch matrix at 1730 cm − 1 . A smoother and more compact surface network was observed in thin films made with MFS than in NFS-based thin films. These observations suggest that the synergistic application of physical and chemical modification techniques significantly alters the functional properties of starch, thereby enhancing its suitability for food packaging applications.